Various types of warning lights, as well as accessory mirrors, have been used for years by many governmental and non-governmental agencies, including police and fire departments and towing services. Such lights and related assemblies can be mounted on the roofs, in rear windows, or dashboards of vehicles as a means of alerting persons approaching the vehicles to the existence of hazardous conditions.
Although warning lights have often been used alone, it is well known that their effectiveness for alerting persons is enhanced by use of accessory mirrors. Each of the mirrors reflects light from the warning light's lamp in a single predetermined direction, thus having the effect of providing multiple flash patterns to an observer. It is known that increasing the number of flashes produced by the light increases the ability of the warning light to draw attention to itself, thereby increasing the light's overall effectiveness.
Several light/mirror arrangements have been used in commercially available systems to increase the number of flashes seen by observers. One such arrangement uses a lamp having a parabolic reflector which rotates through 360.degree., giving the appearance that the lamp itself is rotating. Four planar mirrors are positioned lateral to the lamp in a generally semi-circular configuration such that light from the lamp is reflected by all four mirrors sequentially. The four mirrors are further arranged such that light reflected by each mirror is directed along predetermined parallel light paths (i.e., toward an observer). Upon operation, this device provides a series of five flashes. This increases the effectiveness of the warning light over a single flashing light.
Of course, the effectiveness of the warning light further increases as a greater number of flashes are produced by the apparatus. However, problems arise when one attempts to obtain additional flashes by merely extending the methodology used in the heretofore described arrangement. Although placement of additional mirrors in the same semi-circular configuration around the lamp would seem to offer an easy solution, practical difficulties arise when using this approach. For one, the width of the mirrors cannot be so limited as to cause the flashes to lose their individuality, thereby becoming, in a sense, "blended" together. In such a case, distinguishing individual flashes becomes difficult for an observer since all of the flashes appear to be emanating from the same source, thereby defeating the effectiveness associated with the concept of multiple mirror systems. Moreover, use of additional mirrors forces the forwardmost mirrors to be oriented almost parallel to the predetermined light path, substantially reducing their effectiveness.
Presently known methods would resolve such problems by increasing the radius of the semi-circle such that additional mirrors can be accommodated. This, however, has the undesirable effect of increasing the overall width and depth of the mirror assembly. Such a size increase would render the assembly bulky, making it difficult to handle and store. Further, if used on the dashboard of a vehicle, it would protrude excessively into the passenger compartment of a vehicle, possibly impairing the vision of the vehicle's driver.
A further method for increasing a warning light's effectiveness is to adjust the rate of flashing of a warning light such that the light's effectiveness is maximized. This is best explained by reference to the light's use in a vehicle. When a warning light is mounted on a vehicle which is traveling toward an observer, a certain number of flashes must be generated by the light in order to provide an adequate level of warning to the observer. Translating this principle as regarding a vehicle which is moving at a relatively fast rate of speed, an increased flash rate is required to provide an observer with an adequate number of warning flashes to allow recognition of the oncoming vehicle. Conversely, if the vehicle is stationary or moving at a relatively lower rate of speed, a slower flash rate can be used. Further, use of such slower flash rate when the vehicle is travelling relatively slowly or when it is stationary allows the light to remain in contact with an observer's eye for a longer period of time, thus increasing the effectiveness of the warning light. Thus, lights having only a single flash rate are not desirable for use in situations where a vehicle will be both parked and moving at various rates of speed while the light is operating.
Also affecting the effectiveness of a warning light are the colors of light reaching an observer. Generally, the more colors displayed by a light, the greater its effectiveness.
An additional consideration regarding the operation and effectiveness of a warning light is that it is sometimes desirable to have lamps in warning lights which appear to rotate 360.degree., while at other times lamps which appear to oscillate back and forth are more desirable. Presently available warning lights are generally manufactured in two versions: a first type which rotates the light from the lamp 360.degree. by use of a rotating reflector and a second type which rotates the light from the lamp in an oscillating motion by use of an oscillating reflector. Generally, there are no known mechanical method or warning light designs which would allow one type of light to be modified easily and inexpensively to produce a light of the other type.
With regard to the construction of warning lights, present methods of assembly are quite labor and material intensive. Many methods involve the assembly of the various parts using screws and other small fastening devices. The use of such fasteners not only serves to increase the cost of the light, but also increases the labor cost component. For example, upon fastening each component to another, an assembly worker must first locate the proper fastener, properly position the fastener, and then, in the case of a screw, twist the fastener into place. For a warning light that has several components, this can become very time-consuming as well as inefficient.